GPS receivers with multiple GPS antennas are known in the prior art. Examples of such systems are described in U.S. Pat. Nos. 5,341,301; 5,185,610; and 5,177,493. In these systems, dedicated serial correlating hardware is coupled to each GPS antenna That is, for each GPS antenna, there is corresponding serial correlator hardware. Thus, when a GPS receiver includes several GPS antennas, there will be considerable additional hardware required for each GPS antenna. This additional hardware adds to the cost and weight of such a system. Therefore, such systems are not favored despite the fact that multiple GPS antennas tend to improve the performance of GPS receivers due to the problems from partial or complete blockage of GPS signals which plague GPS receivers.
GPS antennas, because of the blockage problem, tend to be mounted in such a way that they protrude from the device or object which carries the receiver. In this way, the antenna can have an unobstructed view of the sky and any GPS satellites in view at any particular time. Consequently, it is possible to place a GPS receiver in a backpack and mount the antenna as a rigid post on the back of the backpack to provide an unobstructed view of the sky. However, no GPS receivers have been placed in garments along with the GPS antenna, such as the flexible strip antenna on the garment.
The combination of GPS systems and other communications is receiving considerable interest, especially in the areas of personal and property tracking. An example of such a combination is shown in U.S. Pat. No. 5,225,842. The communication link allows a GPS receiver located on a mobile person or object to transmit its accurately determined position to remote locations which monitor this activity. Applications of the technology include security, truck fleet tracking, emergency response, inventory control, etc. The prior art has performed such combinations by mating separate GPS receivers and communication systems using suitable electronic interfaces between the two, for example, serial communication ports, etc. Moreover, these systems use conventional serial correlating approaches to acquiring and tracking GPS satellite signals.